Question

I am having issues writing a query and was hoping someone might be able to offer some advice. The data is related to the geology of bore holes. The From and To fields are the depth down the bore hole.

table1:

holeID --- | --- From ---|---To---|---FMN---|---Rocktype ---|
MW1------|-------0-------|---10---|-----X-----|--------13-------|
MW1------|-------10-----|---20---|-----X-----|--------122------|
MW1------|-------20-----|---30---|-----Y-----|--------177------|
MW1------|-------30-----|---40---|-----Y-----|--------146------|
MW1------|-------40-----|---50---|-----Z-----|--------145-------|
MW1------|-------50-----|---60---|-----X-----|--------1----------|
MW1------|-------60-----|---70---|-----X-----|--------123-------|
MW1------|-------70-----|---80---|-----X-----|--------121-------|
MW1------|-------80-----|---90---|-----Z-----|--------120-------|

Which I would like to condense to:

holeID --- | --- From ---|---To---|---FMN---|
MW1------|-------0-------|---20---|-----X-----|
MW1------|-------20-----|---40---|-----Y-----|
MW1------|-------40-----|---50---|-----Z-----|
MW1------|-------50-----|---80---|-----X-----|
MW1------|-------80-----|---90---|-----Z-----| 

Answer 1

SQL Fiddle

select holeid, "from", "to", fmn
from (
    select
        holeid,
        first_value("from") over(partition by p order by "from") as "from",
        first_value("to") over(partition by p order by "to" desc) as "to",
        fmn
    from (
        select
            holeid, "from", "to", fmn,
            count(p or null) over(partition by holeid order by "from") p
        from (
            select
                holeid, "from", "to", fmn,
                lag(fmn, 1, '') over(partition by holeid order by "from") != fmn p
            from table1
        ) s
    ) s
) s
group by 1, 2, 3, 4
order by 1, 2